Introduction of the Calendar

!! Happy 2018 !!

In the world of the ancients time of day had very little meaning See “Development of Time Zones”. Most people got up at sunrise and went to bed at sunset. However, the time of year was extremely important, especially as far as planting and harvesting was concerned, so, as far back as 800BC, early calendars, based on either sun cycles or moon cycles began to appear.

The original Roman calendar was said to have been invented by Romulus, the first king of Rome, around 753 BCE. This calendar started the year in March (Martius) and consisted of 10 months, with 6 months of 30 days and 4 months of 31 days. The winter season was not assigned to any month, so the calendar year only lasted 304 days with 61 days unaccounted for in the winter.

Soon after becoming Roman dictator, in 46 BC, Julius Caesar decided that the traditional Roman calendar, based on earlier Etruscan moon cycles, was in dire need of reform. Having been around for some 700 years, the Roman calendar attempted to follow the lunar cycle but frequently fell out of phase with the seasons and had to be corrected. In addition, the pontifices, the Roman college of priests charged with overseeing the calendar, often abused its authority by adding days to extend political terms or interfere with elections.

In designing his new calendar, Caesar enlisted the aid of an Alexandrian astronomer by the name of Sosigenes, who advised him to do away with the lunar cycle entirely and follow the solar year, as the Egyptians did. The year was calculated to be 365 and 1/4 days, so Caesar added 67 days to 45 B.C., deciding that 46 B.C. should begin on January 1, rather than in March. He also decreed that every four years a day be added to February, thus theoretically keeping his calendar from falling out of step. Shortly before his assassination in 44 B.C., he changed the name of the fifth month, which was Quintilis, to Julius (July) after himself. Later, the month of Sextilis (the sixth month) was renamed Augustus (August) after his successor.

Celebration of New Year’s Day in January fell out of practice during the Middle Ages, and even those who strictly adhered to the Julian calendar did not observe the New Year exactly on January 1. The reason for this was that Caesar and Sosigenes failed to calculate the correct value for the solar year. They thought the year was 365.25 days, but it actually turned out to be 365.242199 days. It doesn’t seem like much, merely 11 minutes per year, but over the course of 1000 years it added up to 10 days.

The Roman Catholic church became aware of this problem, and in the 1570s Pope Gregory XIII commissioned Jesuit astronomer Christopher Clavius to come up with a new calendar. In 1582, the Gregorian calendar was implemented, omitting 10 days for that year and establishing the new rule that only one of every four centennial years should be a leap year. Since then, people around the world have gathered en masse on January 1 to celebrate the precise arrival of the New Year, perhaps with a drink of whiskey.

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